Passivity and its breakdown on zirconium in high temperature nitric acid

Kajimura, Haruhiko; Nagano, Hiroo

doi:10.1016/0010-938x(90)90117-n

Cited by 17 publications

(11 citation statements)

References 3 publications

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“…The polarization curve of zircaloy-4 exhibited two characteristic potential regions. This is in good agreement with reported literature where polarization curve for zirconium in 3 M nitric acid at 100 o C exhibited characteristic primary, secondary and tertiary potential regions [11]. Potentiodynamic polarization curves for the zircaloy-4 TIG and EB weld were shown in Fig.…”

Section: Potentiodynamic Anodic Polarisationsupporting

confidence: 89%

“…According to Kajimura et.al [11], the stability of zirconium oxide also might be weakened with entry of hydrogen ions into the cation defect of the film, thus accelerated dissolution of zirconium occurs through the porous oxide film. The breakdown of passivity of zircaloy-4 at 1.5 V in our study also would be due to the reactions 3 and 4 as suggested by Kajimura et.al [11].…”

Section: Potentiodynamic Anodic Polarisationmentioning

confidence: 98%

“…SCC (SSRT test) of zirconium in 3 N nitric acid at 100 o C occurred with cleavage-like transgranular fracture in the secondary potential region where passive films broke down [11]. In the present study passive films were grown on zircaloy-4 at different potentials in the secondary potential region in order to understand the nature of films formed at breakdown and repassivation potentials.…”

Section: Passive Film Growthmentioning

confidence: 99%

“…The breakdown of passivity of zirconium in nitric acid at characteristic potential region was due to dissolution according to the following chemical reactions [11].…”

Section: Potentiodynamic Anodic Polarisationmentioning

confidence: 99%

“…Hence polarization behaviour and surface characteristics of passive films formed at transition potentials are useful in understanding the susceptibility of zirconium alloys to SCC in nitric acid medium. Kajimura et.al [11] studied the passivity and breakdown of zirconium in high temperature nitric acid, and three characteristic potential regions were observed, i.e., primary, secondary and tertiary potential regions and reported that SCC occurs in the secondary potential region. In the present work an attempt was made to study; the polarization behaviour of zircaloy-4 and its welds in 11.5 M nitric acid, and characteristics of passive films grown in the secondary potential region.…”

Section: Introductionmentioning

confidence: 97%

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Electrochemical and surface studies on zircaloy-4 exposed to concentrated nitric acid medium

Shankar

Mudali

2009

Trans Indian Inst Met

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Zircaloy-4 has been considered as a candidate material for dissolver and evaporators in nuclear fuel reprocessing plants involving nitric acid of high concentrations at high temperatures. The present work deals with the electrochemical studies and surface analysis of passive films on zircaloy-4 and its welds in 11.5 M nitric acid medium. Potentiodynamic polarization technique was employed to study the corrosion behaviour of the alloy in both base and welded (Manual TIG and electron beam (EB) welding) conditions. The polarization curves for zircaloy-4 and its welds exhibited a distinct breakdown of passivity at 1.5 V (SCE) and repassivation, after showing a region of stable passivation. The characterization of passive films by SEM, XRD and LRS, grown at different potentials in 11.5 M nitric acid are presented. The surface morphology and phase analysis of passive films grown at higher potentials showed the presence of monoclinic ZrO 2 . The phases present in the passive film grown electrochemically in 11.5 M nitric acid at 2.0 V and by autoclaving are found to be similar. The presence of characteristic 1040 cm -1 Raman peak from the sample passivated at 1.2 V indicate that the oxide present consist of nanometer size grains of monoclinic zirconia.

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Section: Potentiodynamic Anodic Polarisationsupporting

confidence: 89%

Section: Potentiodynamic Anodic Polarisationmentioning

confidence: 98%

Section: Passive Film Growthmentioning

confidence: 99%

“…The breakdown of passivity of zirconium in nitric acid at characteristic potential region was due to dissolution according to the following chemical reactions [11].…”

Section: Potentiodynamic Anodic Polarisationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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